Aircraft having Versatile Door Systems

ABSTRACT

A versatile door system for an aircraft includes forward and aft door assemblies. The forward door assembly includes a forward hingeable door hingeably coupled to the airframe proximate a forward location of an aircraft opening and a forward slidable door slidably coupled to the forward hingeable door. The aft door assembly includes an aft hingeable door hingeably coupled to the airframe proximate an aft location of the aircraft opening and an aft slidable door slidably coupled to the aft hingeable door. In a closed configuration, the forward hingeable door, the forward slidable door, the aft hingeable door and the aft slidable door are securably disposed within the aircraft opening. In operation, the forward hingeable door, the forward slidable door, the aft hingeable door and the aft slidable door are individually operable to collectively provide access to a selectable width of the aircraft opening.

TECHNICAL FIELD OF THE DISCLOSURE

The present disclosure relates, in general, to door systems for aircraftand, in particular, to versatile door systems for aircraft includingmultiple door assemblies each having multiple doors that areindividually operable to collectively provide access to a selectableportion of the aircraft opening.

BACKGROUND

Conventional, helicopters have a limited top speed due to the problem ofretreating blade stall, in which the rotor blade on the retreating sideof the rotor disc in forward flight experiences a loss of lift due tothe rotorcraft's linear forward flight velocity exceeding the rotorblade's minimum angular velocity for lift production. Attempts have beenmade to overcome retreating blade stall and to increase the top speed ofrotorcraft. For example, various compound helicopter designs have beenattempted that utilize lift compounding, propulsion compounding or bothto improve top speed. Lift compounding may be achieved by adding wingsto the fuselage to partially offload the lift requirement from the mainrotor during forward flight. Propulsion compounding may be achieved byadding auxiliary propulsive systems such as propellers or jets topartially or fully offload the forward thrust requirement from the mainrotor during forward flight. Utilizing both wings for lift compoundingand auxiliary propulsive systems for propulsion compounding may bereferred to as fully compounding. It has been found, however, that dueto the positioning of the wings and/or the auxiliary propulsive systemson the rotorcraft fuselage as well as the contour of the aircraftafterbody, compound helicopters often have limited space for anaftwardly sliding door, particularly when a wide opening is desired forenabling multi-role capabilities.

SUMMARY

In a first aspect, the present disclosure is directed to a versatiledoor system for an aircraft having an airframe with an aircraft opening.The door system includes a forward door assembly and an aft doorassembly. The forward door assembly includes a forward hingeable doorand a forward slidable door. The forward hingeable door is hingeablycoupled to the airframe proximate a forward location of the aircraftopening. The forward slidable door is slidably coupled to the forwardhingeable door. The aft door assembly includes an aft hingeable door andan aft slidable door. The aft hingeable door is hingeably coupled to theairframe proximate an aft location of the aircraft opening. The aftslidable door is slidably coupled to the aft hingeable door. In a closedconfiguration, the forward hingeable door, the forward slidable door,the aft hingeable door and the aft slidable door are securably disposedwithin the aircraft opening. In operation, the forward hingeable door,the forward slidable door, the aft hingeable door and the aft slidabledoor are individually operable to collectively provide access to aselectable width of the aircraft opening.

In certain embodiments, the forward slidable door may have a closedposition in which the forward slidable door is disposed within theaircraft opening and is longitudinally aligned with the forwardhingeable door. The forward slidable door may also have an open positionin which the forward slidable door is slid forward and into an exteriorposition relative to the forward hingeable door. In such embodiments,the forward hingeable door may have a closed position in which theforward hingeable door is disposed within the aircraft opening and anopen position in which the forward hingeable door is pivoted forwardrelative to the forward location of the aircraft opening, together withthe forward slidable door. Also, in such embodiments, the aft slidabledoor may have a closed position in which the aft slidable door isdisposed within the aircraft opening and is longitudinally aligned withthe aft hingeable door. The aft slidable door may also have an openposition in which the aft slidable door is slid aft and into an exteriorposition relative to the aft hingeable door. Additionally, in suchembodiments, the aft hingeable door may have a closed position in whichthe aft hingeable door is disposed within the aircraft opening and anopen position in which the aft hingeable door is pivoted aft relative tothe aft location of the aircraft opening, together with the aft slidabledoor.

In some embodiments, in an open configuration of the door system, theforward slidable door is in the open position, the forward hingeabledoor is in the closed position, the aft slidable door is in the closedposition and the aft hingeable door is in the closed position such thatthe door system provides access to about a quarter width of the aircraftopening. In certain embodiments, in an open configuration, the forwardslidable door is in the closed position, the forward hingeable door isin the closed position, the aft slidable door is in the open positionand the aft hingeable door is in the closed position such that the doorsystem provides access to about a quarter width of the aircraft opening.In some embodiments, in an open configuration, the forward slidable dooris in the open position, the forward hingeable door is in the openposition, the aft slidable door is in the closed position and the afthingeable door is in the closed position such that the door systemprovides access to about a half width of the aircraft opening. Incertain embodiments, in an open configuration, the forward slidable dooris in the open position, the forward hingeable door is in the closedposition, the aft slidable door is in the open position and the afthingeable door is in the closed position such that the door systemprovides access to about a half width of the aircraft opening.

In some embodiments, in an open configuration, the forward slidable dooris in the closed position, the forward hingeable door is in the closedposition, the aft slidable door is in the open position and the afthingeable door is in the open position such that the door systemprovides access to about a half width of the aircraft opening. Incertain embodiments, in an open configuration, the forward slidable dooris in the open position, the forward hingeable door is in the openposition, the aft slidable door is in the open position and the afthingeable door is in the closed position such that the door systemprovides access to about a three quarter width of the aircraft opening.In some embodiments, in an open configuration, the forward slidable dooris in the open position, the forward hingeable door is in the closedposition, the aft slidable door is in the open position and the afthingeable door is in the open position such that the door systemprovides access to about a three quarter width of the aircraft opening.In certain embodiments, in an open configuration, the forward slidabledoor is in the open position, the forward hingeable door is in the openposition, the aft slidable door is in the open position and the afthingeable door is in the open position such that the door systemprovides access to about a full width of the aircraft opening.

In some embodiments, when the forward slidable door is in the openposition, the forward slidable door is secured against movement relativeto the forward hingeable door. In certain embodiments, when the aftslidable door is in the open position, the aft slidable door is securedagainst movement relative to the aft hingeable door. In someembodiments, in the closed configuration, the forward hingeable door,the forward slidable door, the aft hingeable door and the aft slidabledoor are latched to the airframe. In certain embodiments, the doorsystem includes a rail system having a forward upper rail, a forwardlower rail, an aft upper rail and an aft lower rail. In suchembodiments, the forward upper rail and the aft upper rail may becoupled to the airframe, the forward lower rail may be coupled to theforward hingeable door and the aft lower rail may be coupled to the afthingeable door such that the forward slidable door travels on theforward upper rail and the forward lower rail between open and closedpositions and the aft slidable door travels on the aft upper rail andthe aft lower rail between open and closed positions.

In some embodiments, the forward hingeable door may be operable torotate between about ninety degrees and about one hundred degreesrelative to the forward location of the aircraft opening. In certainembodiments, the aft hingeable door may be operable to rotate betweenabout ninety degrees and about one hundred degrees relative to the aftlocation of the aircraft opening. In some embodiments, the forwardslidable door may have an interior door handle and an exterior doorhandle for opening and closing the forward slidable door. In certainembodiments, the aft slidable door may have an interior door handle andan exterior door handle for opening and closing the aft slidable door.In some embodiments, the forward hingeable door may have an interiordoor handle for opening and closing the forward hingeable door. Incertain embodiments, the aft hingeable door may have an interior doorhandle for opening and closing the aft hingeable door.

In a second aspect, the present disclosure is directed to an aircraftthat includes an airframe having an aircraft opening and a versatiledoor system coupled to the airframe. The door system includes a forwarddoor assembly and an aft door assembly. The forward door assemblyincludes a forward hingeable door and a forward slidable door. Theforward hingeable door is hingeably coupled to the airframe proximate aforward location of the aircraft opening. The forward slidable door isslidably coupled to the forward hingeable door. The aft door assemblyincludes an aft hingeable door and an aft slidable door. The afthingeable door is hingeably coupled to the airframe proximate an aftlocation of the aircraft opening. The aft slidable door is slidablycoupled to the aft hingeable door. In a closed configuration, theforward hingeable door, the forward slidable door, the aft hingeabledoor and the aft slidable door are securably disposed within theaircraft opening. In operation, the forward hingeable door, the forwardslidable door, the aft hingeable door and the aft slidable door areindividually operable to collectively provide access to a selectablewidth of the aircraft opening.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the features and advantages of thepresent disclosure, reference is now made to the detailed descriptionalong with the accompanying figures in which corresponding numerals inthe different figures refer to corresponding parts and in which:

FIGS. 1A-1B are schematic illustrations of a compound rotorcraft havinga versatile door system in accordance with embodiments of the presentdisclosure;

FIGS. 2A-2I are schematic illustrations of a versatile door system foran aircraft in various positions providing access to selectable widthsof the aircraft opening in accordance with embodiments of the presentdisclosure;

FIGS. 3A-3B are exterior and interior views of a versatile door systemfor an aircraft in accordance with embodiments of the presentdisclosure; and

FIG. 4 is an enlarged view of a rail system a versatile door system foran aircraft in accordance with embodiments of the present disclosure.

DETAILED DESCRIPTION

While the making and using of various embodiments of the presentdisclosure are discussed in detail below, it should be appreciated thatthe present disclosure provides many applicable inventive concepts,which can be embodied in a wide variety of specific contexts. Thespecific embodiments discussed herein are merely illustrative and do notdelimit the scope of the present disclosure. In the interest of clarity,all features of an actual implementation may not be described in thisspecification. It will of course be appreciated that in the developmentof any such actual embodiment, numerous implementation-specificdecisions must be made to achieve the developer's specific goals, suchas compliance with system-related and business-related constraints,which will vary from one implementation to another. Moreover, it will beappreciated that such a development effort might be complex andtime-consuming but would nevertheless be a routine undertaking for thoseof ordinary skill in the art having the benefit of this disclosure.

In the specification, reference may be made to the spatial relationshipsbetween various components and to the spatial orientation of variousaspects of components as the devices are depicted in the attacheddrawings. However, as will be recognized by those skilled in the artafter a complete reading of the present disclosure, the devices,members, apparatuses, and the like described herein may be positioned inany desired orientation. Thus, the use of terms such as “above,”“below,” “upper,” “lower” or other like terms to describe a spatialrelationship between various components or to describe the spatialorientation of aspects of such components should be understood todescribe a relative relationship between the components or a spatialorientation of aspects of such components, respectively, as the devicesdescribed herein may be oriented in any desired direction. As usedherein, the term “coupled” may include direct or indirect coupling byany means, including by mere contact or by moving and/or non-movingmechanical connections.

Referring to FIGS. 1A-1B in the drawings, an aircraft having a versatiledoor system of the present disclosure is schematically illustrated andgenerally designated 10. In the illustrated embodiment, the aircraft isdepicted as a rotorcraft in the form of a helicopter and more preciselyin the form of a compound helicopter, which may be referred to herein ashelicopter 10. Helicopter 10 includes an airframe 12 having a fuselage14, wings 16 and wings 18. In the illustrated embodiment, wings 16extend laterally from a forward portion of fuselage 14 and wings 18extend laterally from an aft portion of fuselage 14. Wings 16, 18provide a means for lift compounding responsive to the forward airspeedof helicopter 10 that offloads a portion of the lift requirements from amain rotor assembly 20. Although wings 16 are depicted as straight wingsand wings 18 are depicted as aft swept wings, it will be appreciatedthat wings 16, 18 may be of a wide variety of shapes, sizes andconfigurations, depending upon the performance characteristics desired.

Main rotor assembly 20 is depicted as a single main rotor with fiverotor blades 22 extending radially outward from a main rotor hub 24.Although main rotor assembly 20 has been depicted as having five rotorblades 24 with a particular design, it will be appreciated that mainrotor assembly 20 may have other numbers of rotor blades both greaterthan or less than five and rotor blades 22 may be of a wide variety ofshapes, sizes and configurations, depending upon the performancecharacteristics desired. Main rotor assembly 20 is coupled to fuselage14 and is rotatable relative thereto. The pitch of rotor blades 22 canbe collectively and/or cyclically manipulated by a pitch controlassembly (not visible) to selectively control direction, thrust and liftof helicopter 10.

Helicopter 10 is powered by a turboshaft engine located in a tail cone26 of fuselage 14. The engine provides torque and rotational energy tomain rotor assembly 20 via a drive shaft, a main rotor gearbox and amain rotor shaft (not visible). Helicopter 10 includes an auxiliarypropulsion system that provides propulsion compounding for helicopter 10in the form of ducted fans 28 that are coupled to outboard ends of wings18. Ducted fans 28 may having variable or fixed pitch blades and arepreferably variable speed ducted fans. In the illustrated embodiment,ducted fans 28 are driven by inline mounted electric motors that arepowered by batteries and/or an electric generator driven by the engineof helicopter 10. In other embodiments, ducted fans 28 could bemechanically driven by the engine of helicopter 10 via suitableclutching, shafting and gear systems.

In the illustrated embodiment, ducted fans 28 operate as the anti-torquesystem for helicopter 10 to counteracting the torque exerted on fuselage14 by main rotor assembly 20. In other embodiments, helicopter 10 mayinclude a dedicated anti-torque system such as a tail rotor assemblythat is rotatably coupled to tail cone 26. Such a tail rotor assemblymay have variable pitch tail rotor blades whose pitch is changeable by apitch change mechanism to control the anti-torque thrust. In anotherexample, the tail rotor blades may be fixed pitch and may generateanti-torque thrust responsive to variable rotational speed. In such anembodiment, the anti-torque system may include a variable speed electricmotor for rotating the tail rotor assembly. In other embodiments, theanti-torque system may include a hydraulic motor or the tail rotorassembly may be mechanically driven by a tail rotor drive shaft coupledto the main rotor gearbox.

From takeoff through the low speed cruise regime of helicopter 10,engine power is directed to main rotor assembly 20. As helicopter 10increases forward velocity, wings 16, 18 provide lift compounding byunloading a portion of the lift requirement from main rotor system 20.In addition, as the power requirement on the engine is reduced inforward flight, available engine power can be extracted by engaging anelectric generator that provides electrical power to ducted fans 28 toprovide additional forward thrust to accelerate helicopter 10 to thehigh speed cruise regime. Importantly, the use of ducted fans 28 allowshelicopter 10 to achieve increased forward airspeed.

In the illustrated embodiment, helicopter 10 has a retractable land gearsystem 30 that is depicted in the deployed positioned such thathelicopter 10 is configured for ground operations. It should be notedthat helicopter 10 may be a multi-role helicopter suitable for missionsincluding transport of troops, internal and/or external lifts, medevacoperations, search and rescue missions, special operations and cargotransportation to name a few. Helicopter 10 includes a large aircraftopening 32 and a versatile door system 34 to facilitate the variedrequirements for such multi-role access in and out of helicopter 10. Inthe illustrated embodiment, versatile door system 34 includes a forwarddoor assembly 36 and an aft door assembly 38 depicted in the fully openconfiguration in FIG. 1A and the closed configuration in FIG. 1B.

Forward door assembly 36 includes a forward hingeable door 36 a and aforward slidable door 36 b. Forward hingeable door 36 a is hingeablycoupled to airframe 12 proximate a forward location of aircraft opening32. Forward slidable door 36 b is slidably coupled to forward hingeabledoor 36 a. Aft door assembly 38 includes an aft hingeable door 38 a andan aft slidable door 38 b. Aft hingeable door 38 a is hingeably coupledto airframe 12 proximate an aft location of aircraft opening 32. Aftslidable door 38 b is slidably coupled to aft hingeable door 38 a. Inthe closed configuration of versatile door system 34, forward hingeabledoor 36 a, forward slidable door 36 b, aft hingeable door 38 a and aftslidable door 38 b are securably disposed within aircraft opening 32,thereby preventing access to aircraft opening 32. As discussed herein,forward hingeable door 36 a, forward slidable door 36 b, aft hingeabledoor 38 a and aft slidable door 38 b are individually operable tocollectively provide access to a selectable width of aircraft opening32. Preferably, forward door assembly 36 rotates between about ninetydegrees and about one hundred degrees forward relative to aircraftopening 32 and aft door assembly 38 rotates between about ninety degreesand about one hundred degrees aft relative to aircraft opening 32 suchthat neither forward door assembly 36 nor aft door assembly 38 contactother airframe components such as wings 16, 18 during opening or closingoperations.

It should be appreciated that helicopter 10 is merely illustrative of avariety of aircraft that can implement the embodiments disclosed herein.Indeed, versatile door system 34 may be implemented on any aircraft.Other aircraft implementations can include hybrid aircraft, tiltwingaircraft, tiltrotor aircraft, unmanned aircraft, multirotor air taxis,gyrocopters, fixed wing aircraft, drones and the like. As such, thoseskilled in the art will recognize that versatile door system 34 can beintegrated into a variety of aircraft configurations. It should beappreciated that even though aircraft are particularly well-suited toimplement the embodiments of the present disclosure, non-aircraftvehicles and devices can also implement the embodiments.

Referring additionally to FIGS. 2A-2I of the drawings, the versatileoperations of door system 34 will now be described. Each of forwardhingeable door 36 a, forward slidable door 36 b, aft hingeable door 38 aand aft slidable door 38 b has an open position and a closed positionsuch that forward hingeable door 36 a, forward slidable door 36 b, afthingeable door 38 a and aft slidable door 38 b collectively provideaccess to selectable widths of aircraft opening 32 including a quarterwidth of aircraft opening 32, a half width of aircraft opening 32, athree quarter width of aircraft opening 32 and a full width of aircraftopening 32. For example, forward slidable door 36 b has a closedposition in which forward slidable door 36 b is securably disposedwithin aircraft opening 32 and is longitudinally aligned with and aft offorward hingeable door 36 a. Forward slidable door 36 b has an openposition in which forward slidable door 36 b is slid forward and into anexterior position relative to forward hingeable door 36 a, as best seenin FIG. 2B. In the open position, forward slidable door 36 b is securedagainst sliding movement relative to forward hingeable door 36 a by alink assembly 40 that locks forward slidable door 36 b and forwardhingeable door 36 a together, as best seen in FIG. 2I. Forward hingeabledoor 36 a has a closed position in which forward hingeable door 36 a issecurably disposed within aircraft opening 32. Forward hingeable door 36a has an open position in which forward hingeable door 36 a is pivotedforward relative to aircraft opening 32, as best seen in FIG. 2G.Preferably, forward slidable door 36 b is placed in the open positionprior to placing forward hingeable door 36 a in the open position suchthat forward slidable door 36 b is rotated together with forwardhingeable door 36 a between the open and closed positions.

Aft slidable door 38 b has a closed position in which aft slidable door38 b is securably disposed within aircraft opening 32 and islongitudinally aligned with and forward of aft hingeable door 38 a. Aftslidable door 38 b has an open position in which aft slidable door 38 bis slid aft and into an exterior position relative to aft hingeable door38 a, as best seen in FIG. 2C. In the open position, aft slidable door38 b is secured against sliding movement relative to aft hingeable door38 a by a link assembly 42 that locks aft slidable door 38 b and afthingeable door 38 a together, as best seen in FIG. 2I. Aft hingeabledoor 38 a has a closed position in which aft hingeable door 38 a issecurably disposed within aircraft opening 32. Aft hingeable door 38 ahas an open position in which aft hingeable door 38 a is pivoted aftrelative to aircraft opening 32, as best seen in FIG. 2F. Preferably,aft slidable door 38 b is placed in the open position prior to placingaft hingeable door 38 a in the open position such that aft slidable door38 b is rotated together with aft hingeable door 38 a between the openand closed positions.

In FIG. 2A, versatile door system 34 is in the closed configuration inwhich forward hingeable door 36 a is in the closed position, forwardslidable door 36 b is in the closed position, aft hingeable door 38 a isin the closed position and aft slidable door 38 b is in the closedposition. In FIG. 2B, versatile door system 34 is in a first openconfiguration in which forward slidable door 36 b is in the openposition, forward hingeable door 36 a is in the closed position, aftslidable door 38 b is in the closed position and aft hingeable door 38 ais in the closed position. In the illustrated open configuration,versatile door system 34 provides access to about a quarter width ofaircraft opening 32. In FIG. 2C, versatile door system 34 is in a secondopen configuration in which forward slidable door 36 b is in the closedposition, forward hingeable door 36 a is in the closed position, aftslidable door 38 b is in the open position and aft hingeable door 38 ais in the closed position. In the illustrated open configuration,versatile door system 34 provides access to about a quarter width ofaircraft opening 32.

In FIG. 2D, versatile door system 34 is in a third open configuration inwhich forward slidable door 36 b is in the open position, forwardhingeable door 36 a is in the closed position, aft slidable door 38 b isin the open position and aft hingeable door 38 a is in the closedposition. In the illustrated open configuration, versatile door system34 provides access to about a half width of aircraft opening 32. In FIG.2E, versatile door system 34 is in a fourth open configuration in whichforward slidable door 36 b is in the open position, forward hingeabledoor 36 a is in the open position, aft slidable door 38 b is in theclosed position and aft hingeable door 38 a is in the closed position.In the illustrated open configuration, versatile door system 34 providesaccess to about a half width of aircraft opening 32. In FIG. 2F,versatile door system 34 is in a fifth open configuration in whichforward slidable door 36 b is in the closed position, forward hingeabledoor 36 a is in the closed position, aft slidable door 38 b is in theopen position and aft hingeable door 38 a is in the open position. Inthe illustrated open configuration, versatile door system 34 providesaccess to about a half width of aircraft opening 32.

In FIG. 2G, versatile door system 34 is in a sixth open configuration inwhich forward slidable door 36 b is in the open position, forwardhingeable door 36 a is in the open position, aft slidable door 38 b isin the open position and aft hingeable door 38 a is in the closedposition. In the illustrated open configuration, versatile door system34 provides access to about a three quarter width of aircraft opening32. In FIG. 2H, versatile door system 34 is in a seventh openconfiguration in which forward slidable door 36 b is in the openposition, forward hingeable door 36 a is in the closed position, aftslidable door 38 b is in the open position and aft hingeable door 38 ais in the open position. In the illustrated open configuration,versatile door system 34 provides access to about a three quarter widthof aircraft opening 32. In FIG. 2I, versatile door system 34 is in aneighth open configuration in which forward slidable door 36 b is in theopen position, forward hingeable door 36 a is in the open position, aftslidable door 38 b is in the open position and aft hingeable door 38 ais in the open position. In the illustrated open configuration,versatile door system 34 provides access to about a full width ofaircraft opening 32.

Referring additionally to FIGS. 3A-3B of the drawings, exterior andinterior views of versatile door system 34 are presented. As discussedherein, versatile door system 34 includes forward door assembly 36including forward slidable door 36 b and forward hingeable door 36 a andaft door assembly 38 including aft slidable door 38 b and aft hingeabledoor 38 a. Forward slidable door 36 b has both an exterior handle 44 aand an interior handle 44 b that are operably coupled to upper and lowerlatch assemblies via suitable cabling and an actuation mechanismdisposed within forward slidable door 36 b, only lower latch assembly 46a being visible. Lower latch assembly 46 a includes a latch 48 a thatselectively extends below forward slidable door 36 b and is selectivelyreceived into a slot in airframe 12 along the bottom of aircraft opening32 to secure forward slidable door 36 b thereto when in the closedposition. The upper latch assembly includes a latch 48 b thatselectively extends above forward slidable door 36 b and is selectivelyreceived into a slot in airframe 12 along the top of aircraft opening 32to secure forward slidable door 36 b thereto when in the closedposition. Exterior handle 44 a and interior handle 44 b are operable toshift latches 48 a, 48 b between extended and retracted positions torelease forward slidable door 36 b from airframe 12 when it is desiredto open forward slidable door 36 b.

Forward slidable door 36 b is slidable on a forward rail system 50 thatincludes a lower rail 52 a and a pair of upper rails 52 b, 52 c. Lowerrail 52 a is positioned within forward hingeable door 36 a. Upper rail52 b is supported by airframe 12 near the top of aircraft opening 32, asbest seen in FIG. 4. Upper rail 52 c is positioned within forwardhingeable door 36 a. Forward slidable door 36 b includes a lower sliderbearing 54 a that slidably engages lower rail 52 a. Forward slidabledoor 36 b also includes an upper slider bearing 54 b that sequentiallyslidably engages upper rails 52 b, 52 c. The aft ends of upper rail 52 band lower rail 52 a are curved such that forward slidable door 36 bshifts outwardly when forward slidable door 36 b is slid forward towardthe open position such that forward slidable door 36 b moves to anexterior position relative to forward hingeable door 36 a when operatedto the open position.

Aft slidable door 38 b has both an exterior handle 56 a and an interiorhandle 56 b that are operably coupled to upper and lower latchassemblies via suitable cabling and an actuation mechanism disposedwithin aft slidable door 38 b, only lower latch assembly 58 a beingvisible. Lower latch assembly 58 a includes a latch 60 a thatselectively extends below aft slidable door 38 b and is selectivelyreceived into a slot in airframe 12 along the bottom of aircraft opening32 to secure aft slidable door 38 b thereto when in the closed position.The upper latch assembly includes a latch 60 b that selectively extendsabove aft slidable door 38 b and is selectively received into a slot inairframe 12 along the top of aircraft opening 32 to secure aft slidabledoor 38 b thereto when in the closed position. Exterior handle 56 a andinterior handle 56 b are operable to shift latches 60 a, 60 b betweenextended and retracted positions to release aft slidable door 38 b fromairframe 12 when it is desired to open aft slidable door 38 b.

Aft slidable door 38 b is slidable on an aft rail system 62 thatincludes a lower rail 64 a and a pair of upper rails 64 b, 64 c. Lowerrail 64 a is positioned within aft hingeable door 38 a. Upper rail 64 bis supported by airframe 12 near the top of aircraft opening 32, as bestseen in FIG. 4. Upper rail 64 c is positioned within aft hingeable door38 a. Aft slidable door 38 b includes a lower slider bearing 66 a thatslidably engages lower rail 64 a. Aft slidable door 38 b also includesan upper slider bearing 66 b that sequentially slidably engages upperrails 64 b, 64 c. The forward ends of upper rail 64 b and lower rail 64a are curved such that aft slidable door 38 b shifts outwardly when aftslidable door 38 b is slid aft toward the open position such that aftslidable door 38 b moves to an exterior position relative to afthingeable door 38 a when operated to the open position.

Forward hingeable door 36 a has an interior handle 68 that is operablycoupled to upper and lower latch assemblies via suitable cabling and anactuation mechanism disposed within forward hingeable door 36 a, onlylower latch assembly 70 a being visible. Lower latch assembly 70 aincludes a latch 72 a that selectively extends below forward hingeabledoor 36 a and is selectively received into a slot in airframe 12 alongthe bottom of aircraft opening 32 to secure forward hingeable door 36 athereto when in the closed position. The upper latch assembly includes alatch 72 b that selectively extends above forward hingeable door 36 aand is selectively received into a slot in airframe 12 along the top ofaircraft opening 32 to secure forward hingeable door 36 a thereto whenin the closed position. Interior handle 68 is operable to shift latches72 a, 72 b between extended and retracted positions to release forwardhingeable door 36 a from airframe 12 when it is desired to open forwardhingeable door 36 a.

Forward hingeable door 36 a pivots relative to a forward beam ofairframe opening 32 on a pair of hinge assemblies 74 a, 74 b. Thedistance and speed of travel of forward hingeable door 36 a duringopening and closing operations may be regulated by forward door strut 76that is coupled between airframe 12 and forward hingeable door 36 a.Preferably, forward door strut 76 and/or hinge assemblies 74 a, 74 blimit the rotational travel of forward hingeable door 36 a to betweenabout ninety degrees and about one hundred degrees such that forwardhingeable door 36 a will not contact other airframe members duringoperations. Forward door strut 76 also maintains forward hingeable door36 a in the open position. In the illustrated embodiment, forwardhingeable door 36 a should only be operated between the open and closedpositions when forward slidable door 36 b has moved to its exteriorposition relative to forward hingeable door 36 a and been securedtherein.

Aft hingeable door 38 a has an interior handle 78 that is operablycoupled to upper and lower latch assemblies via suitable cabling and anactuation mechanism disposed within aft hingeable door 38 a, only lowerlatch assembly 80 a being visible. Lower latch assembly 80 a includes alatch 82 a that selectively extends below aft hingeable door 38 a and isselectively received into a slot in airframe 12 along the bottom ofaircraft opening 32 to secure aft hingeable door 38 a thereto when inthe closed position. The upper latch assembly includes a latch 82 b thatselectively extends above aft hingeable door 38 a and is selectivelyreceived into a slot in airframe 12 along the top of aircraft opening 32to secure aft hingeable door 38 a thereto when in the closed position.Interior handle 78 is operable to shift latches 82 a, 82 b betweenextended and retracted positions to release aft hingeable door 38 a fromairframe 12 when it is desired to open aft hingeable door 38 a.

Aft hingeable door 38 a pivots relative to an aft beam of airframeopening 32 on a pair of hinge assemblies 84 a, 84 b. The distance andspeed of travel of aft hingeable door 38 a during opening and closingoperations may be regulated by aft door strut 86 that is coupled betweenairframe 12 and aft hingeable door 38 a. Preferably, aft door strut 86and/or hinge assemblies 84 a, 84 b limit the rotational travel of afthingeable door 38 a to between about ninety degrees and about onehundred degrees such that aft hingeable door 38 a will not contact otherairframe members during operations. Aft door strut 86 also maintains afthingeable door 38 a in the open position. In the illustrated embodiment,aft hingeable door 38 a should only be operated between the open andclosed positions when aft slidable door 38 b has moved to its exteriorposition relative to aft hingeable door 38 a and been secured therein.

Even though forward slidable door 36 b, forward hingeable door 36 a, aftslidable door 38 b and aft hingeable door 38 a have each been describedas having a latch system that is actuated responsive to operation ofinterior and/or exterior handles, in other embodiments, some or all offorward slidable door 36 b, forward hingeable door 36 a, aft slidabledoor 38 b and aft hingeable door 38 a could alternatively oradditionally have dedicated latch assemblies that are independent of theinterior and exterior handles and that are manually or automaticallyoperated to secure forward slidable door 36 b, forward hingeable door 36a, aft slidable door 38 b and/or aft hingeable door 38 a to airframe 12when forward slidable door 36 b, forward hingeable door 36 a, aftslidable door 38 b and/or aft hingeable door 38 a are in their closedpositions.

The foregoing description of embodiments of the disclosure has beenpresented for purposes of illustration and description. It is notintended to be exhaustive or to limit the disclosure to the precise formdisclosed, and modifications and variations are possible in light of theabove teachings or may be acquired from practice of the disclosure. Theembodiments were chosen and described in order to explain the principalsof the disclosure and its practical application to enable one skilled inthe art to utilize the disclosure in various embodiments and withvarious modifications as are suited to the particular use contemplated.Other substitutions, modifications, changes and omissions may be made inthe design, operating conditions and arrangement of the embodimentswithout departing from the scope of the present disclosure. Suchmodifications and combinations of the illustrative embodiments as wellas other embodiments will be apparent to persons skilled in the art uponreference to the description. It is, therefore, intended that theappended claims encompass any such modifications or embodiments.

What is claimed is:
 1. A versatile door system for an aircraft having anairframe with an aircraft opening, the door system comprising: a forwarddoor assembly including a forward hingeable door and a forward slidabledoor, the forward hingeable door hingeably coupled to the airframeproximate a forward location of the aircraft opening, the forwardslidable door slidably coupled to the forward hingeable door; and an aftdoor assembly including an aft hingeable door and an aft slidable door,the aft hingeable door hingeably coupled to the airframe proximate anaft location of the aircraft opening, the aft slidable door slidablycoupled to the aft hingeable door; wherein, in a closed configuration,the forward hingeable door, the forward slidable door, the aft hingeabledoor and the aft slidable door are securably disposed within theaircraft opening; and wherein, the forward hingeable door, the forwardslidable door, the aft hingeable door and the aft slidable door areindividually operable to collectively provide access to a selectablewidth of the aircraft opening.
 2. The door system as recited in claim 1wherein the forward slidable door has a closed position in which theforward slidable door is disposed within the aircraft opening and islongitudinally aligned with the forward hingeable door and an openposition in which the forward slidable door is slid forward and into anexterior position relative to the forward hingeable door; wherein theforward hingeable door has a closed position in which the forwardhingeable door is disposed within the aircraft opening and an openposition in which the forward hingeable door is pivoted forward relativeto the forward location of the aircraft opening together with theforward slidable door; wherein the aft slidable door has a closedposition in which the aft slidable door is disposed within the aircraftopening and is longitudinally aligned with the aft hingeable door and anopen position in which the aft slidable door is slid aft and into anexterior position relative to the aft hingeable door; and wherein theaft hingeable door has a closed position in which the aft hingeable dooris disposed within the aircraft opening and an open position in whichthe aft hingeable door is pivoted aft relative to the aft location ofthe aircraft opening together with the aft slidable door.
 3. The doorsystem as recited in claim 2 wherein, in an open configuration, theforward slidable door is in the open position, the forward hingeabledoor is in the closed position, the aft slidable door is in the closedposition and the aft hingeable door is in the closed position such thatthe door system provides access to about a quarter width of the aircraftopening.
 4. The door system as recited in claim 2 wherein, in an openconfiguration, the forward slidable door is in the closed position, theforward hingeable door is in the closed position, the aft slidable dooris in the open position and the aft hingeable door is in the closedposition such that the door system provides access to about a quarterwidth of the aircraft opening.
 5. The door system as recited in claim 2wherein, in an open configuration, the forward slidable door is in theopen position, the forward hingeable door is in the open position, theaft slidable door is in the closed position and the aft hingeable dooris in the closed position such that the door system provides access toabout a half width of the aircraft opening.
 6. The door system asrecited in claim 2 wherein, in an open configuration, the forwardslidable door is in the open position, the forward hingeable door is inthe closed position, the aft slidable door is in the open position andthe aft hingeable door is in the closed position such that the doorsystem provides access to about a half width of the aircraft opening. 7.The door system as recited in claim 2 wherein, in an open configuration,the forward slidable door is in the closed position, the forwardhingeable door is in the closed position, the aft slidable door is inthe open position and the aft hingeable door is in the open positionsuch that the door system provides access to about a half width of theaircraft opening.
 8. The door system as recited in claim 2 wherein, inan open configuration, the forward slidable door is in the openposition, the forward hingeable door is in the open position, the aftslidable door is in the open position and the aft hingeable door is inthe closed position such that the door system provides access to about athree quarter width of the aircraft opening.
 9. The door system asrecited in claim 2 wherein, in an open configuration, the forwardslidable door is in the open position, the forward hingeable door is inthe closed position, the aft slidable door is in the open position andthe aft hingeable door is in the open position such that the door systemprovides access to about a three quarter width of the aircraft opening.10. The door system as recited in claim 2 wherein, in an openconfiguration, the forward slidable door is in the open position, theforward hingeable door is in the open position, the aft slidable door isin the open position and the aft hingeable door is in the open positionsuch that the door system provides access to about a full width of theaircraft opening.
 11. The door system as recited in claim 2 wherein,when the forward slidable door is in the open position, the forwardslidable door is secured against movement relative to the forwardhingeable door; and wherein, when the aft slidable door is in the openposition, the aft slidable door is secured against movement relative tothe aft hingeable door.
 12. The door system as recited in claim 1wherein, in the closed configuration, the forward hingeable door, theforward slidable door, the aft hingeable door and the aft slidable doorare latched to the airframe.
 13. The door system as recited in claim 1further comprising a rail system including a forward upper rail, aforward lower rail, an aft upper rail and an aft lower rail; wherein theforward upper rail and the aft upper rail are coupled to the airframe;wherein the forward lower rail is coupled to the forward hingeable door;wherein the aft lower rail is coupled to the aft hingeable door; whereinthe forward slidable door travels on the forward upper rail and theforward lower rail between open and closed positions; and wherein theaft slidable door travels on the aft upper rail and the aft lower railbetween open and closed positions.
 14. The door system as recited inclaim 1 wherein the forward hingeable door is operable to rotate betweenabout ninety degrees and about one hundred degrees relative to theforward location of the aircraft opening; and wherein the aft hingeabledoor is operable to rotate between about ninety degrees and about onehundred degrees relative to the aft location of the aircraft opening.15. The door system as recited in claim 1 wherein the forward slidabledoor has an interior door handle and an exterior door handle for openingand closing the forward slidable door; and wherein the aft slidable doorhas an interior door handle and an exterior door handle for opening andclosing the aft slidable door.
 16. The door system as recited in claim 1wherein the forward hingeable door has an interior door handle foropening and closing the forward hingeable door; and wherein the afthingeable door has an interior door handle for opening and closing theaft hingeable door.
 17. An aircraft comprising: an airframe having anaircraft opening; and a versatile door system coupled to the airframe,the door system including: a forward door assembly including a forwardhingeable door and a forward slidable door, the forward hingeable doorhingeably coupled to the airframe proximate a forward location of theaircraft opening, the forward slidable door slidably coupled to theforward hingeable door; and an aft door assembly including an afthingeable door and an aft slidable door, the aft hingeable doorhingeably coupled to the airframe proximate an aft location of theaircraft opening, the aft slidable door slidably coupled to the afthingeable door; wherein, in a closed configuration, the forwardhingeable door, the forward slidable door, the aft hingeable door andthe aft slidable door are securably disposed within the aircraftopening; and wherein, the forward hingeable door, the forward slidabledoor, the aft hingeable door and the aft slidable door are individuallyoperable to collectively provide access to a selectable width of theaircraft opening.
 18. The aircraft as recited in claim 17 wherein theaircraft further comprises a rotorcraft.
 19. The aircraft as recited inclaim 17 wherein the aircraft further comprises a helicopter.
 20. Theaircraft as recited in claim 17 wherein the aircraft further comprises acompound helicopter.